Cancer and aging are travel companions. In a first view this relation may seem awkward, but the events that have allowed to establish this improbable bond go back to the year 1951 when for the first time it was possible to keep in lab culture conditions an immortal human cellular line, of cells that are in constant growth. The same barriers that separate normal cells from immortal cells connect in an intimate way the "how" with the "why" of aging.
The complexity of aging and biological cancer prevent from being able to extract easy generalizations. Cancer and aging are fostered by the accumulation of cellular damage. Those mechanism protecting the cells from damage will provide protection for both cancer and aging. On the other hand, cancer and longevity require a durable potential of cell proliferation and, thus, the mechanisms limiting the indefinite cell proliferation (like for example the telomeric shortening or cellular senescence) will provide protection against cancer, but a the same time favor aging. The net equilibrium between these two types of mechanism, those diminishing the amount of cell damage (protecting at the same time from cancer and aging) and those preventing from the excessive cell proliferation (which normally do not limit the average life of the individual, but that in protected environments may contribute to aging) would be what would ensure a healthy existence (free of cancer and of the complications derived from aging) to most individuals during the young and adult life periods.
In agreement with the theory of evolution that has been accepted for 100 years, namely darwinism, the persistence of individuals that cannot contribute reproductively to the next generation is an astonishing example of evolutionary inefficiency. Darwinism postulates that the species surviving a long evolutionary process are those that contribute to the following generation with more descendants (which is how genetic heritage disseminates). From this perspective, the persistence of long-lived individuals who cannot further contribute to perpetuating the species has alway been an evolutionary paradox: What are these individuals -male or female- good for once they have surpassed the age of procreation and transmission of their own genetic pool? Particularly, the recent discovery of a very old individual lacking all of its teeth dating from 1.8 million years ago in the Dmanisi site in Georgia, has starkly obliged us to reconsider this issue. There is no register of another fossil hominid showing such a pronounced loss of dentition and reshaping of the jaw. The younger Pleistocene individuals found in Bau de l’Aubésier and La Chapelle-aux-Saints always show a much more complete dentition at the time of death. Although it is worth noting that the later are neanderthals, much more evolved, with larger brains, and a more advanced culture. In addition, samples of of non-human primates with such a degradation of the masticatory system are extremely rare. Considering that currently there are no apes in temperate regions like Dmanisi, we can only guess the behavioral consequences in the framework of the bio-cultural data preserved in the site. D3444 and D3900 were recovered from the B1 layer of block 2, which also contained stone artifacts and eight animal bone remains marked with percussion signs made by stone tools, indicating the processing of animal corpses for consumption of meat, which is a common finding in other hominid sites of the Pliocene and Pleistocene. Meat can indeed be the key to the success of these hominids inhabiting high latitudes, especially during winter, and the consumption of soft tissues like marrow or brains, could allow for the survival of individuals with limited masticatory systems. Due to the lack of fruit trees in the surroundings of Dmanisi, it is obvious that this elderly individual had to be taken care of by the group to which it belonged,who probably processed the food it consumed. In the framework of the harsh life conditions experienced by hominids at the beginning of the Pleistocene, what is the biological meaning of keeping individuals who could not take care of themselves and had already fulfilled their reproductive role? Whatever it may be, what is clear is that this type of cooperative behavior was already established in hominids two million years ago.
The key to this and other similar cases could maybe lie in incomprehensible processes within the limits of strict individual selection. Indeed, there are a certain number of characters that are not specific to individuals, but are at the general level of the species, and that nevertheless seem to be clearly favored by evolution. Even though they trespass the limits of individuality, these characters favor the survival of individuals from a supra-individual level, from the perspective of the species. This is what has been named "species selection" or "selection at the level of species" (a heterodox variation of darwinism), and usually affects the "life history" of the individual, the characters that fundamentally affect the age of birth, growth, reproduction and death within a population (those called demographic factors, not specific to individuals but to the entire species). The species that tend to show in their life history the existence of long-lived specimens will be better prepared for short-time climatic crisis. This way, the elders are some kind of memory of the system that may occasionally allow for the survival of the entire group in adverse conditions. These strategies have developed preferently in migrating organisms like birds, elephants, some turtles and dinosaurs, and of course in ourselves, probably during the early scavenger phase of the Homo habilis, when we migrated from Africa towards the rest of the Old World.
The social changes resulting are normally limited to the increasing weight of the elder. But nevertheless it affects all stages of life and all the relationships implicated in social reproduction, from the intergenerational relations to the relations between sexes. The population maintenance efficiency is substantially improved in Spain and the elder are an essential part of the social and economical general process of modernization. I will defend in this conference that demographic aging does not produce the severe problems that are traditionally assigned to it, but that have never been tested, and that elder people do not have as their main trait being a burden for the rest of society, but the other way around.
Philosophy has not been a great help until now for deepen within the phenomenon of aging. Philosophers have traditionally been interested in the human being as subject of knowledge and as the a producer of moral and policy. The philosophers of morality have taken their time to think about big topics like freedom, virtue, or obligation, but they have not thought about vulnerability and human finitude. Only the Stoics, and some of their followers -like Montaigne or Schopenhauer- take time to speak about the different shapes of human finitude, which is more evidently reflected by the decay and decadence that are associated with getting old. Accepting the limitations of age, and at the same time, make the most out of the experiences lived; seeing old age not only as a problem, but as an opportunity; is the perspective from which practical philosophy should address the topic of aging.
Each period and each culture have their own conception of aging. The question that should be posed is what is the meaning of getting old in our world and in our time: what does aging mean for the individual getting old; what does it mean for a society that is becoming older, but that is not keen on making old age visible; how to face aging from policy and how it should be done from ethic. There is a tendency to limit the phenomenon of aging to the realm of medicine. This is reductionism, because aging is not a disease, although it is often accompanied by diseases and ailments. Aging poses questions that are related with big philosophical questions: the sense of life, the personal identity, the relationship with others, social justice, or personal autonomy. Questions that need to abandon abstraction and get contrasted with a reality that cannot be ignored if we pretend that philosophy helps us to live better.